1. Field of the Invention
The present invention relates to a guide apparatus for vertical movement of a stage. More particularly, the invention relates to the apparatus suitable for vertically guiding the stage of a microscope whereby to enable the observation of sizable specimens, a liquid crystal display panel and others, for example.
2. Related Background Art
A guide apparatus for vertical movement of a stage used for a microscope is to support the stage vertically movable on which to place a specimen. Traditionally, a vertical movement guiding apparatus of the kind used for a microscope supports its stage in a cantilever fashion to make it movable vertically for the observation of a small specimen such as slide glass using two sets of guide members each comprising a movable portion and a base portion which make a pair having rollers or balls therebetween.
Now, in recent years, the sizes of the specimens to be examined have become larger, such as a wafer and liquid crystal glass substrate. Along with this, there is a tendency that the stage is made larger. Also, at the same time, the contents of the specimen to be examined have become more minute, necessitating precise observations and precise measurements using a microscope or other optical equipment. However, the foregoing apparatus for vertically guiding a stage is supported in a cantilever fashion. As a result, there is a disadvantage that the stage is inclined or bent when it is made larger. Because of this, any precise observations and precise measurements cannot be conducted. Thus, there is a need for a guide apparatus for vertical movement of a stage having a rigidity strong enough to prevent the stage from being inclined, at the same time, being capable of supporting the stage movable in the vertical direction. For example, it is conceivable to provide a guide apparatus for vertical movement of a stage as shown in FIG. 5 to FIG. 7. Now, hereinafter, the description will be made of this guide apparatus for vertical movement of a stage. In this respect, this guide apparatus for vertical movement of a stage is disclosed in Japanese Patent Application Laid-open No. 3-58011.
As shown in FIG. 5 and FIG. 6, a stage 1 is mounted in a hollow stage supporting member 2. This stage supporting member 2 has through holes 4 and 5 on its side face and is inserted into an outer frame 10. This outer frame 10 has a through hole 8, and supports the stage supporting member 2 vertically movable through four sets of guide members 3. The guide member 3 has a guided portion 3a fixed to the stage supporting member 2 and a guide portion 3b fixed to the outer frame. Between the guided portion 3a and guide portion 3b, a plurality of balls or rollers are arranged in a line in the vertical direction.
In this way, the vertical movement guide apparatus is fixed to a base of a microscope which is not shown. The stage 1 and the stage supporting member 2 can be moved vertically along guide members 3 by operating a one-shaft handle 6. The light beam emitted from a light source 9 is reflected by a reflection mirror 7 fixed to the outer frame 10 by way of the through hole 8 of the outer frame 10 and the through hole 4 of the stage supporting member 2 and is guided into the stage 1.
As described above, this guide apparatus for vertical movement of a stage is capable of securing the light guide to illuminate a specimen, at the same time supporting the stage supporting member, that is the stage 1 eventually, form both sides thereof by means of the four sets of the guide members 3. Therefore, this guide apparatus for vertical movement of a stage has a high rigidity so that the stage 1 will not be inclined when the center of gravity of the stage 1 is shifted, and that the stage supporting member 2, that is the stage 1 eventually, is movably supported in the vertical direction with stability.
Nevertheless, a conventional guide apparatus for vertical movement of a stage of the kind has the drawbacks given below. This conventional guide apparatus for vertical movement of a stage makes it necessary to provide the four sets of the guide members exactly in the same length and enable all the four sets to hold the stage supporting member evenly. As a result, all the four sets of the guide members, the stage supporting member to which these guide member are fixed, and the outer frame are machined equally with high precisions; thus not only making it extremely difficult to machine each part, but also increasing its manufacturing cost significantly. If not machined with a high precision, the four sets of the guide members cannot be in parallel, hindering smooth vertical movement of the stage.
Also, as shown in FIG. 7, the stage supporting member 2, having the through holes 4 and 5 formed on its side face, lowers the rigidity of the stage supporting member itself. Consequently, when the center of gravity of the stage 1 is shifted, the stage supporting member 2 tends to be bent or twisted. Furthermore, since the stage supporting member 2 reacts to restore itself from this bend or torsion, it becomes easily vibratory. Thus, not only the stage 1 is inclined, bent, or vibrated, but also the parallelism of the four sets of the guides is lost to hinder the smooth vertical movement of the stage 1.